Your body is using energy preparing for a possible pregnancy, thus, you get cold, immune system is lowered ect.. Your immune system can also lower itself, because A.It's often the immune system which stops sperm from getting to the egg (sperm is foreign to a womens' body, so it trys to kill them off) and B.The immune system is often the cause of miscarriage, the is foetus also foreign to the womens' body.
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